Diplex telephone connection.



A. W. EBELING. DIPLEX TELEPHONE CONNECTION. APPLICATION FILED JULY 7, 1909.

Patented June 7, 1910.

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v earns r nrcfi accuse: WILHELM EBE ING, or ennnnorrnnnnns, GERMANY, Assrcnon TO SIEMENS a EALSKE A. G., or BERLIN, GERMANY, A CORPORATION or GERMANY.

I Specification of Letters Patent.

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Patented June 7,1910.

Application filed July 7, 1909. Serial No. 506,380.

To all whom it may concern:

" Be it'known that ill, AlJGUS'I WILimLM EBELING, a subject of the German Emperor,

near Berlin and residing at Charlottenburg, Germany, have invented certain new and useful Improvements in Diplex Telephone Connections, of which the following is a specification.

The subject-matter of my invention isa ance coils in the same at definite intervals which are as uniform as possible. Inthis manner it is possible to make telephone lines separated by materially greater distances. Endeavors are constantly being made to make telephonic .working more profitable over long distances, this being still relatively expensive. One way of doing this is af-' forded by the well-known diplex telephone connection. The use of the diplex telephone connection in the case of double lines equipped with Pupin coils is connected with certain difiicu-lties however. For equipping double lines with P'upin coils so-called double coils have been used, in general, heretofore, z'. e. coils having two windingson a common iron core, of which the one winding is always interpolated in the one branch and the other winding in the other branch of the double line. If double lines equipped: in this manner were employed in diplex telephone connections, as will be readily understood the efiect intended by the inductance coils for the combined double line would not occur, since in consequence of the deranged current in this event, the self-induction coils wound on common cores would reciprocally cancellone another in their effect. If'instead of double .coils single coils were employed, the use of lines equipped in such inanuer would'indeedbepossible in the di-- plex telephone connection, but these coils present great difficulties inasmuch'as it is very difiicult in practice to make single coils whlch' possess and retain exactly equal elec- 'trical values which is absolutely necessary in order that the currents in the lead and return of a double line may be as exactly equal as possible. If the currents are not exactly tuned, very disturbing cross-talk is met within diplex working.

Now a primary object of my invention is to remove these defects; making use of the materially more advantageous double coils, I attain this object by interpolating a special set of double coils in each double line for each mode of working these lines, namely in such manner that they take into account-the different directions of current.

In order that my invention may be ciearly understood I will now describe the same with reference to the accompanying drawing in which one embodiment is diagrammatically represented by way of example.

Referring to the drawing, 1 and II denote two double lines, whose branches a, b are equipped with double coils c and d. To the standard equipment of the two double lines the double coils 0 would solely belong which are distributed along the entire don ble line at definite, but referably uniform intervals and whose win ings, as shown, are arranged on common cores. The direction in which the windings c are wound and the interpolation of the windings 0 in the branches of the double lines must be such that, having regard to the direction 'of-current occurring during normal working, which direction will always be opposite in the two windings, the iron core is magnetized in the same sense. -If it were wished to unite such double lines equipped only with coils c in the diplex telephone con-- nection, in this event, as will be readily understood, the self-induction of the windings of the individual coils would reciprocally cancel one another for thecombined double. line, since then both the branches of each double line would conduct the current in the same direction at any time. t cachdouble line he provided, howeverfwith a second set of self-induction coils (Z in such manner that account is taken of the flow of current occurrim iii-the diplex connection, e'. c, by,,the core being magnetized only in the same sense by the two windings when the branches of the double line are traversed by current in the same sense,it is possible to obtain the Pupin effect in the diplex connect-ion also. As is clear, it is .only' necessary to reverse the connection of the one Me lines are therefore loaded by 5 combined double line the coils 0 do not 013-- crate in the normal sense, but that these windings traversed simultaneously now by current of the other reciprocally in their action. he douself-induction in the diplex connection solely by the set of coils (Z. Owing to the employment of two sets of coils increased resistance of thetelephone circuit has to be reckoned with. But since, as described, only one set of coils operative simultaneously, only the pure, direct current resistances come into question which can be selecting suitable coils. Practical tests have shown that the influence of the coils which are inoperative at any time is practically nnnoticeable or only so to a small extent according to the kind of the coils in each instance. In order to maintain the Pupin etfect correct, of course the values of the sellinductions of the coils must be selected suitably, the capacity oi. the kind of conductor and the effective value of the self-induction having to be taken into consideration.

It is obviously not necessary that the two double coils and d be always located in the lines as closed together in pairs as shown in the drawings, but that the additional coils cl may be distributed over the lines at any suitable intervals, however, ternating with the double coils o. It is only necessary that the single coils of the two sets of double coils are all traversed by the cursame direction cancel one ankeptvery small by and the single coils 1n the other line being traversed by the curalways alrent in series in the same sense in one of the two lines (for instance in line a as shown) and that the single coils of the two sets located in the other line (b) are traversed by the current in series, but alternately in the opposite sense.

In the event of an additional telephone circuit being made by further combination of two double lines, which might have a certain importance in cables, the operative coils of the first combination would have to be considered as simple coils. Consequently, it would always be possible to make a further combination beyond that of two double lines to form a third telephone circuit in case of need.

I claim:

.In a diplex telephone connection the combination with the double lines, having a set I of double coils forming the self-induction load according to the lupin system; of an additional setof double coils alternating with the double coils oi said first named set along the lines at suitable intervals, the single coils of the two sets of double coils 'in one of the two lines being all traversed by the current in series and in. the same sense of the two sets located rent in series but. alternately in the opposite sense, for the purpose set forth.

In testimony whereof I have signed my name to this specification in two witnesses.

AUGUST \VILHELM E lVitnesses I'IENRY HAsrnR, lVoLninu'AR IlAUr'r.

BEIJING.

the presence of 

